This invention relates to a fuel supplying system for an internal combustion engine and more particularly to an improved fuel supplying system for acceleration and deceleration conditions.
As is well known, a conventional charge former such as a carburetor incorporates an accelerating pump for discharging additional fuel into the induction passage during acceleration. This additional fuel discharge is provided so as to compensate for the greater inertia of fuel relative to air in changed air flow conditions. That is, when the engine begins to accelerate, the air flow will instantly increase but fuel flow will lag for some period of time due to its greater inertia. The accelerating pump is intended to provide additional fuel so as to make up for this lag. However, conventional accelerating pumps have a specific defect in that they tend to discharge too much of their fuel during the initial trottle opening acceleration condition and not enough at the end of the accelerating cycle. As a result, a large amount of fuel is injected initially at a time when the engine has not begun to accelerate and the air flow has not reached a quantity equivalent to the amount of fuel that is discharged. As a result, there is fuel wastage and poor fuel economy. Also, this tends to cause a leaner that desired mixture during the latter stage of acceleration and acceleration is not as smooth or as rapid as desired.
It is, therefore, a principal object of this invention to provide an improved accelerating system for the fuel discharge of a fuel supply system for an internal combustion engine.
It is a further object of this invention to provide a fuel supply system accelerating arrangement wherein the accelerating fuel flow more closely matches the acceleration of the associated engine.
The operation of the engine on deceleration and particularly during severe decelerations also presents some problems. These problems are again caused by the inertial effects and differences between the fuel and air mixture and the differences in rate of change of flow under transient conditions. These problems are particularly acute in two-cycle engines where the incoming fresh fuel/air mixture is employed to scavenge the residual gases from the combustion chamber. When the throttle valve is suddenly closed and the engine has been running at high speeds, the mixture in the combustion chamber is made up of a large part of residual exhaust gases and poor running and even stalling of the engine can result under extreme decelerations.
It is, therefore, a further object of this invention to provide an improved charge forming device for an internal combustion engine for improving performance under deceleration conditions.
It is another object of this invention to provide a device for supplying fuel to an internal combustion engine on deceleration.